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Optimize the performance of cluster slots for non-continuous slots (#11745)

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This change improves the performance of cluster slots by removing the deferring lengths that are used. Deferring lengths are used in two contexts, the first is for determining the number of replicas that serve a slot (Added in 6.2 as part of a different performance improvement) and the second is for determining the extra networking options for each node (Added in 7.0). For continuous slots, (e.g. 0-8196) this improvement is very negligible, however it becomes more significant when slots are not continuous (e.g. 0 2 4 6 etc) which can happen in production for various users.

The `cluster slots` command is deprecated in favor of `cluster shards`, but since most clients don't support the new command yet I think it's important to not degrade performance here.

Benchmarking shows about 2x improvement, however I wasn't able to get a coherent TPS number since the benchmark process was being saturated long before Redis was, so had to run with multiple benchmarks and merge results. If needed I can add this to our memtier framework. Instead the next section shows the number of usec per call from the benchmark results, which shows significant improvement as well as having a more coherent response in the CoB.

| | New Code | Old Code | % Improvements
|----|----|----- |-----
| Uniform slots| usec_per_call=10.46 | usec_per_call=11.03 | 5.7%
| Worst case (Only even slots)| usec_per_call=963.80 | usec_per_call=2950.99 | 307%

This change also removes some extra white space that I added a when making a code change for adding hostnames.
This commit is contained in:
Madelyn Olson 2023-01-29 18:04:53 -08:00 committed by GitHub
parent 6444214ce4
commit e74a1f3bd9
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1 changed files with 25 additions and 10 deletions
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35
src/cluster.c
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@ -5339,7 +5339,7 @@ void addNodeToNodeReply(client *c, clusterNode *node) {
} else {
serverPanic("Unrecognized preferred endpoint type");
}
/* Report non-TLS ports to non-TLS client in TLS cluster if available. */
int use_pport = (server.tls_cluster &&
c->conn && (c->conn->type != connectionTypeTls()));
@ -5347,40 +5347,55 @@ void addNodeToNodeReply(client *c, clusterNode *node) {
addReplyBulkCBuffer(c, node->name, CLUSTER_NAMELEN);
/* Add the additional endpoint information, this is all the known networking information
* that is not the preferred endpoint. */
void *deflen = addReplyDeferredLen(c);
* that is not the preferred endpoint. Note the logic is evaluated twice so we can
* correctly report the number of additional network arguments without using a deferred
* map, an assertion is made at the end to check we set the right length. */
int length = 0;
if (server.cluster_preferred_endpoint_type != CLUSTER_ENDPOINT_TYPE_IP) {
length++;
}
if (server.cluster_preferred_endpoint_type != CLUSTER_ENDPOINT_TYPE_HOSTNAME
&& sdslen(node->hostname) != 0)
{
length++;
}
addReplyMapLen(c, length);
if (server.cluster_preferred_endpoint_type != CLUSTER_ENDPOINT_TYPE_IP) {
addReplyBulkCString(c, "ip");
addReplyBulkCString(c, node->ip);
length++;
length--;
}
if (server.cluster_preferred_endpoint_type != CLUSTER_ENDPOINT_TYPE_HOSTNAME
&& sdslen(node->hostname) != 0)
{
addReplyBulkCString(c, "hostname");
addReplyBulkCBuffer(c, node->hostname, sdslen(node->hostname));
length++;
length--;
}
setDeferredMapLen(c, deflen, length);
serverAssert(length == 0);
}
void addNodeReplyForClusterSlot(client *c, clusterNode *node, int start_slot, int end_slot) {
int i, nested_elements = 3; /* slots (2) + master addr (1) */
void *nested_replylen = addReplyDeferredLen(c);
for (i = 0; i < node->numslaves; i++) {
if (!isReplicaAvailable(node->slaves[i])) continue;
nested_elements++;
}
addReplyArrayLen(c, nested_elements);
addReplyLongLong(c, start_slot);
addReplyLongLong(c, end_slot);
addNodeToNodeReply(c, node);
/* Remaining nodes in reply are replicas for slot range */
for (i = 0; i < node->numslaves; i++) {
/* This loop is copy/pasted from clusterGenNodeDescription()
* with modifications for per-slot node aggregation. */
if (!isReplicaAvailable(node->slaves[i])) continue;
addNodeToNodeReply(c, node->slaves[i]);
nested_elements++;
nested_elements--;
}
setDeferredArrayLen(c, nested_replylen, nested_elements);
serverAssert(nested_elements == 3); /* Original 3 elements */
}
/* Add detailed information of a node to the output buffer of the given client. */